1. Field of the Invention
The present invention concerns a method for depalletizing stacked containers, of the type wherein containers are lifted in a frictionally engaged manner and are underridden by at least one support base, as well as a device for depalletizing stacked containers, with at least one roller to lift the containers and with a support base.
The invention in particular concerns the depalletizing of containers stacked on a pallet
2. Description of the Prior Art
Individual goods or connected goods containers are typically stacked in multiple layers on a palette and are arranged there for a transport. Given homogeneous palletizing, identical goods (such as beverage containers, for example) are stacked on the pallet. Given mixed palletizing, different goods or goods containers are arranged on a single palette. This is also called mixed commissioning. A wide-spread application is the arrangement of a mixed pallet of goods based on an order of a retailer with a distributor. The goods ordered by retailer are assembled from a storage of the distributor. The desired goods are thereby removed from homogeneous pallets and individually assembled on a delivery pallet according to the customer order. The mixed, commissioned pallet is then delivered to the buyer, i.e. delivered to the retailer.
U.S. Pat. No. 4,453,874 shows a device of the above-described type, with a grabber having a front, free end on which rotatable rollers are mounted. The rollers serve to lift the goods to be taken on one side by means of frictionally engaged contact with a side surface of said goods, such that they can be loaded onto a support base of the grabber that can be moved under the goods for this. Alternatively, a conveyer belt can be provided at the grabber, with which the goods can be transported on said grabber. The rollers can be provided with a friction-increasing relief or a coating; for example, they can be fashioned rubberized. The taken goods package can subsequently be deposited again on another pallet in the reverse order. Such grabbers are generally permanently installed in a system or are mobile, directed via a portal system.
It is disadvantageous that only one single-sided action on the goods is possible, such that a brace is necessary and—since the goods are tilted upon lifting and the distance between brace and lifting roller increases—either the brace or the lifting roller must be elastically arranged, wherein a difficult coordination is to be conducted between elastic yielding force and friction coefficient of the roller.
DE 37 18 601 A1 discloses a depalletizing tool that is mounted on an articulated robot. The tool possesses rigid, blade-like pickup tongues that can engage below and lift the goods packages. United States Patent Application Publication No. 2002/0154986 A1 discloses a lifting plate with very low height that can be slid between layers of goods, thereby raises the upper layer so that a stronger and more stable take-up plate can be slid under the goods package. This tool can also be attached to a robot.
Depalletizing tools known from the prior art also exhibit the disadvantage that the depalletizing process can be sensitively disrupted or, respectively, hindered by a presence of loose objects arranged on the top of a container unit (for example coverings or cover layers in the most varied embodiments or materials). For example, a sliding or canting of such objects during an unloading process can lead to a complete operational failure of a of a known depalletizing tool, with a significant time and repair cost associated therewith.